Henze, MartinMartinHenzeMatzutt, RomanRomanMatzuttHiller, JensJensHillerMöhmer, ErikErikMöhmerZiegeldorf, Jan HenrikJan HenrikZiegeldorfGiet, Johannes van derJohannes van derGietWehrle, KlausKlausWehrle2022-03-0623.11.20212022https://publica.fraunhofer.de/handle/publica/26824410.1109/TCC.2020.3000336In past years, cloud storage systems saw an enormous rise in usage. However, despite their popularity and importance as underlying infrastructure for more complex cloud services, today's cloud storage systems do not account for compliance with regulatory, organizational, or contractual data handling requirements by design. Since legislation increasingly responds to rising data protection and privacy concerns, complying with data handling requirements becomes a crucial property for cloud storage systems. We present PRADA, a practical approach to account for compliance with data handling requirements in key-value based cloud storage systems. To achieve this goal, PRADA introduces a transparent data handling layer, which empowers clients to request specific data handling requirements and enables operators of cloud storage systems to comply with them. We implement PRADA on top of the distributed database Cassandra and show in our evaluation that complying with data handling requirements in cloud storage systems is practical in real-world cloud deployments as used for microblogging, data sharing in the Internet of Things, and distributed email storage.en004journal article